Morphological and optical properties

Scanning or transmission electron microscopy (SEM or TEM, respectively) are typically used for performing morphological characterization of nanomaterials obtained by template synthesis. The resolution of the images is improved if the nanomaterial is separated from the host membrane. 

Nanometals have interesting optical properties, whether they are inside the host template or liberated from it. For example, suspensions of nanoscopic Au particles can be pink, purple, or blue, depending on the diameter of the particles. These colors arise from the plas-mon resonance absorption of the nanometal particle (25). Membranes containing Au nanowires also show this plasmon resonance band, and as a result, such membranes can show a wide variety of colors (42). This absorption in the visible region, typically between 400 and 800 nm for 10-30 nm diameter particles, provides an interesting optical approach to characterizing Au nanowires (5). 

The spectra resulting from the aqueous dispersion of the nanorods removed from the host template show two plasmon resonance bands a strong one at long wavelengths due to the long-axis resonance and a weaker one at shorter wavelengths that originates from the transverse resonance (85). 

All of these optical features are useful in characterizing the shape and spatial distribution of the nanostructures. 

---

Roark S E and Rowlen K L 1993 Atomic force microscopy of thin Ag films. Relationship between morphology and optical properties Chem. Phys. Lett. 212 50... 

Semin D.J., Rowlen K.L., Influence of vapor-deposition parameters on SERS active Ag film morphology and optical-properties, Anat. Chem. 1994 66 4324-4331. 

Gao, X. D. Li, X. M. Yu, W. D. 2004. Morphology and optical properties of amorphous ZnS films deposited by ultrasonic-assisted successive ionic layer adsorption and reaction method. Thin Solid Films 468 43 17. 

Similar measurements were carried out using an external electric field [72], Some differences in morphology and optical properties were measured, depending on the direction of the field with respect to the substrate. It is not clear, from the experimental setup, why the field should influence the deposition, since the field is external and should drop across the air and the glass walls of the reaction vessel. 

THE MORPHOLOGY AND OPTICAL PROPERTIES OF Fe, Cr AND Mg SILICIDE NANOCRYSTALLITES BURIED IN SILICON BY ION IMPLANTATION, PULSED TREATMENTS AND Si OVERGROWTH... 

The morphology and optical properties of Si samples implanted by Fe, Cr and Mg ions have been studied before and after pulsed annealing by laser and ion beams. Ultrahigh vacuum cleaning and epitaxial growth of Si films with thickness up to 500 nm have been carried out for Si with Fe and Cr silicide nanocr>stallites. Optimum conditions of pulsed treatments have been determined for all samples. 

S. Zangooie, H. Arwin, Surface, pore morphology, and optical properties of porous 4H-SiC, J. Electrochem. Soc., 148 G297-G302 (2001). 

Table 9.2 Fractal dimensions of different smokes [88]. Reprinted from J. Aerosol Sci., Vol. 28, Colbeck, L, Atkinson, B. and Johar, Y., The morphology and optical properties of soot produced by different fuels, 715-723. Copyright (1997), with permission from Elsevier.

Grimsdale, A.C., et al. 2002. Correlation between molecular structure, microscopic morphology, and optical properties of poly(tetraalkylindenofluorenes). Adv Funct Mater 12 729. 

Lessons learned from these studies provide valuable guidance to tiie rational design of future generations of PDA-based colorimetric sensors as well as otiier advanced nanomachinery where tire microscopic morphology and optical properties of the material are crucial to its function. 

Of particular interest are the ternary systems of ethylcellulose dissolved in a mixed solvent (acrylic acid - water or acrylic acid - glacial acetic acid) and ethylcellulose/ acrylic acid solution blended with a flexible polymer, polyacrylamide. The conclusions of these studies is that, for cellulosic liquid crystals application, the morphology and optical properties of lyotropic liquid crystals can be adjusted by solvent mixing and blending with other polymers. 

I. Colbeck, B. Atkinson, Y. Johar, The Morphology and Optical Properties of Soot Produced by Different Fuels, /. Aerosol Science, 28 (1997) 715-723. 

The vapour evaporation of thin silver films onto suitable surfaces will produce structures resembling islands for mass thicknesses between 4 and 20 nm. These nanostructures show exceptional stability under normal conditions, but will always have thin oxide layers formed on their surfaces. There are several important experimental factors that will affect strongly the morphology and optical properties of these films and they include the substrate used, substrate temperature, mass thickness, deposition geometry, and evaporation rate. It is very easy to control all of these factors to attain reproducible results, and so film preparation is reduced to a matter of using optimum conditions, and maintaining consistency in experimental methods. 

Jackson, J.B. and N.J. Halas, Silver Nanoshells Variations in Morphologies and Optical Properties. J. Phys. Chem. B., 2001.105 p. 2743-2746. 

In some applications, porous silicon (PSi) is, however, desired to increase the specific surface area (up to 1000 mVcm ). Several books and reviews have been already published about PSi formation mechanisms, morphologies and optical properties (cf [130-133]). Briefly, PSi is usually prepared from (100) Si wafers by constant-current anodization in an ethanolic solution (mixture of HF with ethanol). The characteristics of the pores are determined by the doping of the substrate, the HF concentration and the cturent density used during the anodization process [134-139]. PSi surfaces present =Si-H, =SiH2> and trihydride (-SiHj) sites. Potential steric hindrances could appear most hkely when micropores formation is obtained. It should be mentioned that PSi received increasing interest in the 1990s because of its luminescence properties in the visible range. 

Dian, L, Macek, A.. Niznansky, D., Nemec, I., Vrkoslav, T. et al. (2004) SEM and HRTEM study of porous silicon-relationship between fabrication, morphology, and optical properties. Applied Surface Science, 238, 169-74. 

---